OptionalinstancingOptionalinstancingOptional six cube-face 2D textures (px,py,pz,nx,ny,nz). Prefer
reflectionAtlas on iOS — many simultaneous face samplers still trip
GL_INVALID_OPERATION on WebKit.
Multiplier for the reflection sample — mirrors texture.level.
Cubemap (or other reflection texture) harvested from a Babylon material's
reflectionTexture. Mesh batches sample it like StandardMaterial cubic
reflection; other render modes ignore it.
Single 3×2 atlas of cube faces (px py pz / nx ny nz). One sampler2D — the path that stays valid on iOS WebKit ShaderMaterial draws.